Brakes – Internal-resistance motion retarder – Valve structure or location
Reexamination Certificate
1999-08-31
2001-05-15
Oberleitner, Robert J. (Department: 3613)
Brakes
Internal-resistance motion retarder
Valve structure or location
C188S282600, C188S322140
Reexamination Certificate
active
06230858
ABSTRACT:
TECHNICAL FIELD
This invention relates to fluid dampers for vehicles, and more specifically, to an orifice disc for use as a low speed bypass valve in a valve assembly.
BACKGROUND OF THE INVENTION
Fluid vehicle dampers, such as hydraulic shock absorbers and struts, provide a smooth ride by absorbing forces that are generated by an uneven road surface. Two common types of vehicle fluid dampers are monotube and twin tube shock absorbers, each of which have a cylinder and piston. Twin tube shock absorbers have a valve body located at an end of the piston, commonly referred to as a piston valve, and at a cylinder end, commonly referred to as a base valve. The piston valve moves toward the base valve during compression of the shock absorber and moves away from the base valve during rebound. The valve bodies divide the shock absorbers into several fluid chambers and regulate the flow of fluid from one chamber to another thereby achieving particular ride handling characteristics. Typically, each valve body has a compression and rebound valve assembly located on opposing surfaces of the valve body that regulate fluid flow during the compression and rebound strokes. By modifying the valve assemblies, the ride handling characteristics may be calibrated.
Typically, it may be desirable to have a low speed bypass valve and a high speed bypass valve as part of a valve assembly to provide different degrees of damping depending on the speed at which the shock absorber compresses or rebounds. The valve bodies have inner and outer annular seats that coact directly or indirectly with adjacent low and high speed bypass valves. During low speed movement of the piston, such as vehicle cornering maneuvers, fluid only flows past the low bypass valve while the high bypass valve remains closed. Thus, the low speed bypass valve provides a rate of damping. One prior art low speed bypass valve has incorporated a solid disc-shape structure in abutting relation with the annular seats. The annular seats are coined to form notches through which the fluid may flow during low speed movement of the piston. However, the coining operation requires a library of precision tools to form the notches, which adds cost to the low speed bypass valve. Another prior art low speed bypass valve has incorporated a disc having notches at the perimeter of the disc adjacent to the outer annular seat. When the disc is adjacent to the annular seats, the fluid only flows through the notches in the disc during low speed movement of the piston. However, this type of disc tends to fatigue over time. Therefore, what is needed is a robustly designed low speed bypass valve that is inexpensive.
SUMMARY OF THE INVENTION
The present invention provides a fluid vehicle damper having a cylinder with a valve body. The valve body includes an outer surface adjacent to an interior wall of the cylinder and includes first and second opposing surfaces. The valve body defines first and second fluid chambers within the damper, which are adjacent to the first and second surfaces, respectively. Inner and outer annular seats extend from the first surface and define an annular channel therebetween. At least one fluid passageway is disposed between the annular channel and second surface for providing fluid communication therebetween. A high speed bypass valve assembly is attached to the valve body and is movable between an open position and a closed position adjacent to the annular seats. An orifice disc is interposed between the annular seats and the high speed bypass valve assembly for providing low speed bypass of fluid from the second chamber to the first chamber when the high speed bypass valve assembly is in the closed position. The orifice disc has at least one opening therethrough defined by a contiguous perimeter. The outer annular seat segments the opening into inner and outer passageways. When the damper undergoes low speed movement, fluid flows from the second chamber through the fluid passageway into the annular channel, through the inner passageway around the outer annular seat, and out the outer passageway to the first chamber.
Accordingly, the present invention provides a low speed bypass valve that obviates the need for a coining operation and provides a disc that has an improved fatigue life.
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Moradmand Jamshid Kargar
Neal Robert Alan
Delphi Technologies Inc.
Oberleitner Robert J.
Sigler Robert M.
Talavera Melanie
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